Operating unit for sound-amplifying devices



Jan.'3, 1928. 1,654,741

G. c. LINDSEY OPERATING UNIT FOR SOUND AMPLIIIWL'INGr DEV ICES Filed Feb. 8. '1926- 620L176 6: like??? x1 TTORXE 3 Patented Jan. 3 1 928.

' UNITED STATES GEORGE C. LINDSEY, 01 LOS ANGELES, CALIFORNIA, ASSIGNOR OF NINE THIRTY- SECONDS TO ROBERT TURNER, SEVEN THIRTY-SECONDS TO MICHAEL GOZ ZO, ONE- EIGHTH TO DON EMINGER, AND SIX THIRTY-SECONDS TO VICTOR P. HENDRICK.

OPERATING UNIT FOR SOUND-AMPLIFY ING DEVICES.

Application filed February 8, 1926. Serial No. 86,780.

adjustment-for the vibrating stylus of theunit. v

It is a further object of the invention to provide a vibrating stylus adapted for dependent adjustment of the pressure of the stylus against the sound responsive medium and the spacing'of the vibrator bar of the st lus with relation to the operating coilso the unit.

The invention will be readily understood from the following description of the accompanying drawing in which: Fig. 1 is a vertical section through the improved unit. Fig. 2 is a front elevation of the unit with the casing removed.

Fig. 3 is a transversesection on the line 3-3 of Fig. 1.

Fig. 4. is a side elevation of the unit'showing a modified form of the invention.

Fig. 5 is a detail section on the line 5-5 of Fig. 4.

Fig. 6 is a side elevation of the unit showing a still further modification of the mounting for the same.

The improved operating unit is of general f 1 '14. threaded through base 5 and provided with lock nuts 15, with the ends of the utility for vibrating a sound responsive medium, and may be employed in connection with a sound reproducersuch as set forth in my co-pending' application, Ser. No. 57

l 153, filed Sent. 18, 1925. In this embodiment of the inventionfthe unit directly vibrates a sounding board so as to eliminate the necessity for a diaphragm, and itis for such a specific construction that the unit is particularly adapted.

The sounding board maybe mounted on a suitable support '1, and may comprise Fig. 1:; or a sounding board may be mounted on the underside of the base 1 of a radio.

boards 2 at opposite sides of the support as shown in Fig. 6 or may comprise board 2 at one side only of the support as shown in cabinet A as shown in Fig. 4. The sounding board is preferably curved with its edges secured to its support as shown at 3, and its medial portion spaced from the support to form an'air pocket 4. I v e .Theoperating unit is mounted on'a base 5 which supports a casing 40 enclosing the mechanism, in the form of the invention.

shown in Figs. 1 and 4, the unit is cushioned relative to the sounding board. I As an instance of this arrangement a block 6 (if yieldable cushioning material such as rubber is interposed between one end of the'un it and its support, with a bolt 7 received through the support,-.the cushioning block, I

'andthe fixed end of the unit; and the opposite end of the unit is free for slight swinging movement by yielding of the cushioning block. In the from of the invention illustrated in Fig. 6 the unit is fixed relative to the supportby an interposed nonyielding block 6 and a bolt 7.

The operating unit includes a bar I 12 mounted for vibration by electric impulses in usualmanner, the actuating me'hanism being shown as of standard type employed in radio reception and comprising alaminated bar 8 on the basev 5, with coils 9 mounted thereon and a permanent horseshoe magnet 10 surrounding the coils. The bar 12 is yieldably spaced from coils 9 for vibration of the bar in accordance with impulses transmitted to the coils through wires 13 whichlead to a radio receivingset or other source of electrical impulses.

The mounting for bar 12 comprises screws screws projecting beyond coils 9 and form a ing points 16 on which an end of the bar 12 is supported. An adjusting screw 17 extends through bar-l2 between the screws 14 and is threaded into the base 5; and'the ad justing screw has aflexible washer 18 and a coil spring 19 between its head and the bar 12 in order to press the-end of the bar the bar and having a projecting end which is mounted on a screw 21 carried by the base 5. The end of the leaf spring is a'djustably fixed on screw 21 .by means of nuts 22 threaded on the screw against opposite faces of the spring.

One end of the bar 12is thus lyieldably held against points 16 bythe spring 19, and

A the opposite end of the bar being yieldably supported by spring 20, thecoils 9 cooperate with-the permanent magnet 10 to produce vibrations of the bar; and a stylus projects perpendicularly from the vibrator bar and engages the sounding board of the device to correspondingly vibrate the sounding board I andthereby produce and amplify the sound.

- 7 adapted for vibration between the end sup- The bar 12 and the stylus form a structurewhich in itself is comparatively rigid, but is ports 16 and 20, and the stylus is spaced bec tween said end supports so'that relative adjustment between the ,entire operating unit and. the sounding board will adjust the pres- Wltl1 relation to the supports 16 is also determined in accordance with the tone which it is desired to produce.

In the form of the invention illustrated in' Figs. and 6 the base 5 engages the block .9 surface 27 against which the unit abuts.

interposed between the unit and its support; and the stylus 25 projects from the side of gagement with the sounding board. As'a consequence the pressure of the stylus is against the sounding board when the vibrator bar 12 returns to normal'spaced relation from the coils during the intervals between energizing thereof.

As illustrated in Fig. 4, the position of the operating unit is reversed so that casing 40 abuts against the cushioning block 6; and the stylus 25 projects from the side of the vibrator bar which is toward coils 9, and extends through the base 5 for engagement with the sounding board 2 so that pressure of .the stylus is against the sounding board when the vibrating bar is drawn toward the coils 9 by the energizing of the latter.

v,The stylus of the unit may simply abut against the sounding board as shown in Fi 4, or:it may extend through the sounding board and be fixed, relative thereto by' the nuts 26 as shown in Figs. 1 and 6.

The block between the support and the operating unit on which the unit is mounted is preferably arranged so. that the stylus of the unit is a radius of the curve of the sounding board in order that maximum vibration may be obtained;-and for this purpose the block 6 is provided with an inclined contact The cushioning'block 6 employed in the form of the inventions illustrated in Figs. 1

and 4, normally positions the operating unit so that the pressure of the stylus against the sounding board is released; and the means sure of the stylus against the sounding board and will also adjust the spacing of bar 12 the vibrator bar which is away from coils 9, and extendsthrough the casing 40 for en-' position by yielding of the cushioning block,

in order to adjust the pressure of the stylus against the sounding'board and at the same .time adjust the spacing between vibrator bar .12 and coils 9, preferably comprises an operating cam 30 cooperating with-the unit. The cam maybe j ournaled in bearings 31011 the support 1, so as to press against the unit when the cam shaft 32 is turned; and the cam shaft is arranged for convenient turning and automatic locking in adjusted position, by means of a manually operated key 33 which projects to the exterior of the sounding board and'has a worm driving connection 34 for the cam shaft.

In the form of the invention illustrated in Fig. 6, where the operating unit is rigidly fixed relative to support 1 by means of the n0n-yielding block 6, the pressure of the stylus against the sounding board and the" spacing of the vibrator bar relative to the coils, is regulated by adjustment of the sounding board relative to,the stylus which is fixed thereto. As an instance of this arrangement an operating rod 50 which is I adapted for manual turning, may be axially fixed relative to the sounding board by means of collars 51, and axially adjustable relative to the support 1 by means of the threaded connection 52.

I claim:

1. A sound reproducer comprising a support, a sounding board fixed at its edges to the support with its medial portion spaced from the support, an electro-magnetic actuating means on the support, a vibrator, a

mounting for the vibrator positioning it in normal spaced relation from the actuating means, means for tensioning said mounting to yieldably retain the vibrator, in normal position against movement toward or away from theactuating means, a stylus onthe vibrator engaging the sounding board, and means for dependently adjusting the pressure of the stylus relative to the sounding board and the normal spacing of the vibrator from the actuating means.

2. A sound reproducer comprising a support; an operating unit mounted on the sup: port; a sound responsive medium mounted on the support in spaced relation from the operating unit; said operating unit comprislng an electro-magnetic actuating means, a

vibrator, a mounting for the vibratorposi-' tioning it in normal spaced relation from the actuating means, .means for tensioning said mounting to yieldably retain the vibratorin normal position against movement toward or away from the actuating means, and a stylus on the vibrator engaging the sound responsive medium; and means foradjusting the spacing between I the sound responsive .me-

.dium and the'operating unit and thereby dependently adjust the pressure of the stylus relative to the sound responsive medium and the normal spating of the vibrator from the actuating means.

3. An operating unit for a sound responsive medium comprising electro-magnetic actuating means, a vibrator, mountings for opposite ends of the vibrator positioning it in normal spaced relation from the actuating means, means, for tensioning the mountings at said opposite ends of the vibrator to yieldably retain the vibrator in normal position against movement toward or away from the actuatingmeans, and a stylus on the vibrator adapted to engage the sound responsive medium.

4. An operating unit for a'sound responsive medium comprising electro-magnetic actuating means, an inherently rigid vibrator and stylus, a mounting for the vibrator ositioning it in normal spaced relation rom the actuating means with thestylus engaging the sound responsive medium, said mounting omprising a tensioned pivotal support onthe operating unit for one end of the vibrator and a leaf spring carried by the operating unit and fixed to the other end of the vibrator, and means for adjustingthe relative position of the operating unit and the sound responsive medium so as to dependently adjust the pressure of the stylus relative to the sound responsive medium and the normal spacing of the vibrator from the actuating means.

5. An operating unit for a sound responsive medium comprising electro-magnetic actuating means, an inherently rigid vibrator and stylus, and a mounting positioning the vibrator in normal spaced relation from the actuating means with the stylus engaging the sound responsive medium, said mounting comprising a pivotal support for one end of the vibrator and a leaf spring support for its opposite end whereby the vibrator is ten.- sioned in normal position against movement toward or away from the actuating means.

In testimony whereof he hasafiixed-his signature to this specification, v GEORGE O. LINDSEY. 

